Tag: Borehole Seismic

19 Oct 2016

OptaSense Collaborates with Leading Research Institution to Install Fiber Optic Seismic Array

OptaSense, a QinetiQ company, announces a collaborative research agreement with the Stanford School of Earth, Energy and Environmental Sciences that includes the installation of an on-campus fiber optic seismic array.

Using OptaSense distributed acoustic sensing (DAS) technology to sense ambient noise and seismic energy, the seismic array will enable scientists to conduct research in passive seismology. Located adjacent to a major geologic fault zone, the San Andreas Fault, the seismic array will be used to image subsurface properties that provide scientists a better understanding of the complex geology in the Bay Area.

The seismic array will leverage a two kilometer long, standard telecommunications fiber optic cable. The OptaSense DAS system will transform this fiber into thousands of distributed sensors capable of detecting changes in pressure, temperature and strain. A single fiber can create a seismic array with thousands of channels, allowing for dense sampling of seismic wavefields and the ability to detect weak signals.

Utilizing a Coherent Optical Time Domain Reflectometer, or Interrogator Unit (IU), the OptaSense system sends laser pulses down the length of the fiber to measure and observe changes in the backscattered light, indicating movement in the earth adjacent to the fiber.

In addition to enabling research in seismology, the OptaSense DAS system will support potential studies in fields such as structural engineering, communications, infrastructure monitoring, and security.

“Collaborating with one of the world’s foremost academic institutions is particularly exciting for OptaSense. For the first time, we are putting our DAS technology into the hands of the academic community and working with them to explore new applications and techniques. Through this collaboration we will be able to mature the understanding and expand the capabilities of DAS for the benefit of the wider seismic community,” commented David Hill, Chief Technology Officer at OptaSense.

27 Mar 2016

Microseismic Interferometry: Transforming dots in a box into a 3D seismic image

Traditionally, operators plan and execute a hydraulic fracturing project based in part on available seismic data, which lacks the resolution needed to see fine-scale geophysical features and reservoir extent. Without a detailed understanding of a reservoir’s geophysical characteristics, the chosen fracturing parameters may not be optimal, resulting in diminished performance and wasted money.

OptaSense has released an advanced method of imaging called microseismic interferometry that uses the microseismic events themselves as seismic sources to generate high-resolution three-dimensional images. Using data recorded on either DAS fiber optic tools or conventional three-component receivers, microseismic interferometry  improves upon traditional microseismic processing which produces event locations (dots in a box) along with some event attributes but no image.

OptaSense’s new technique employs thousands of microseismic events to build up a 3D image of the stimulated reservoir volume and supply a high resolution image of the subsurface geology around event locations.

Microseismic interferometry works by gathering data from a long borehole seismic array, ideally with 3C sensors straddling the stimulation zone. The data is then processed in a conventional manner to produce event locations and magnitudes. Following this initial analysis, the full waveform data is processed using interferometry – imaging the P and S wave fields to produce a local image for each microseismic event. These local images are combined into one large 3D volume covering the entire extent of the frac zone.  This analysis can be performed on newly-acquired microseismic data or on existing surveys.

The 3D interferometric image volume can be analyzed using standard seismic analysis tools and can be integrated with existing surface seismic interpretations, well logs, formation tops, horizons or geomechanical analyses to build a better understanding of  the reservoir and its geology. This improved understanding may be particularly useful for planning additional wells in nearby areas or re-fracturing wells in the imaged area.

OptaSense’s microseismic interferometry method extracts high-resolution information from existing data. Customers benefit from optimizing the costs of completion and drilling as they can use the information to plan subsequent fracs in nearby areas, re-fracs in the same formation or for time-lapse reservoir characterization.

To read more, download the paper by clicking here.

12 Sep 2013

DAS 3D VSP in Deepwater

Oil Field Services

Mateeva, A., Mestayer, J., Yang, Z., Lopez, J., Wills, P., Roy, J. and Bown, T., ‘Dual-Well Massive 3D VSP in Deepwater made possible by DAS’, Pages 5062-5066, SEG Annual Meeting, Houston, September 2013

Link

16 Nov 2012

Advances in Distributed Acoustic Sensing for VSP

Oil Field Services

Mateeva, A., Mestayer, J., Cox, B., Kiyashchenko D., Wills, P., Lopez, J., Grandi, S., Hornman, K., Lumens, P., Franzen A., Hill, D., Roy J.,  ‘Advances in Distributed Acoustic Sensing (DAS) for VSP’, SEG Expanded Abstracts Vol. 30, 4253 – 4257, SEG Annual Meeting, Las Vegas, Nevada, November. 2012

Link